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Nitrogen balance and its effects on nitrate-N concentration of groundwater in three intensive cropping systems of North China

KOU Changlin1,2,JU Xiaotang1,ZHANG Fusuo1   

  1. 1Key Laboratory of Plant Nutrition MOA,Key Laboratory of Plant-Soil Interactions MOE,Department of Plant Nutrition,China Agricultural University, Beijing 100094,China;2Institute of Soil and Fertilizer,Henan Academy of Agricultural Sciences,Zhengzhou 450002,China

  • Received:2004-04-12 Revised:2004-10-04 Online:2005-04-18

Abstract: Selecting three main intensive cropping systems of North China,i.e,wheatmaize rotation,plastic greenhouse vegetable,and apple orchard as test objectives,this paper studied their nitrogen (N) budget,soil nitrate-N accumulation,and year-round dynamics of groundwater nitrate-N concentration. The results showed that in plastic greenhouse vegetable cropping system,the annual N input from chemical fertilizers,manure,and irrigation was 1 358,1 881 and 402 kg·hm-2,being 2.5,37.5 and 83.8 folds of the corresponding items in wheat-maize cropping system,and 2.1,10.4 and 68.2 folds in orchard,respectively,and its total N input amounted to 3 656 kg·hm-2,being 5.8 times of the wheat-maize cropping system,and 4.2 times of the orchard.The wet deposition N in the three cropping systems ranged from 14.2 kg·hm-2 to 18.9 kg·hm-2.The N output by wheat-maize, greenhouse vegetable and orchard was 280,329 and 121 kg·hm-2,the N surplus was 349,3 327 and 746 kg·hm-2,and the remained nitrate-N after harvest amounted to 221~275,1 173 and 613 kg·hm-2 in 0~90 cm soil layer,and 213~242,1 032 and 976 kg·hm-2 in 90~180 cm soil layer, respectively. Crop field had a comparatively even distribution of nitrate N in its 0~180 cm soil profile,and a sharp increase of nitrate N throughout the soil profile were found in both greenhouse vegetable and orchard fields.There was an evident nitrate leaching in all three cropping systems.The groundwater in shallow well (<15 m) was severely contaminated in greenhouse vegetable area,with the nitrate-N concentration in 99% of the samples exceeding the maximum permissible limit for drinking water (10 mg·L-1),while 5% of the samples in deep well in vegetable area and in shallow well in orchard and 1% of the samples in deep well in wheat-maize field were exceeded the limit.The nitrate-N concentration exponentially decreased with well depth (m) in greenhouse vegetable area.

Key words: Broadleaved Korean pine forests, Eco climatic suitability, Temperature water effect function, Climate change, Assessment